Simple Chess Defence

It's been a while since my last blog post as I tend to like providing detailed analysis and advice in my writing, but I'll deviate from that today in favour of a simple puzzle to test your skill in defending against an attack, as it's not so easy to find such puzzles in books (though Aagaard's 'Practical Chess Defence' deserves praise for providing numerous such exercises). 

Enjoy the puzzle, and don't forget to play through the notes after solving!